

public class ListNode {
     int val;
    ListNode next;
     ListNode() {}
    ListNode(int val) { this.val = val; }
    ListNode(int val, ListNode next) { this.val = val; this.next = next; }
}
class Solution {
    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
        ListNode nH = new ListNode();
        ListNode tH = nH;

        while(list1 != null && list2 != null){
            if(list1.val > list2.val){
                tH. next = list2;
                list2 = list2.next;
            }else{
                tH. next = list1;
                list1 = list1.next;
            }
            tH = tH.next;
        }

        if(list1 != null){
            tH.next = list1;
        }
        if(list2 != null){
            tH.next = list2;
        }
        return nH.next;
    }
}